Vacuum pouring apparatus



Feb. 14, 1956 United StateS Patent VACUUM POURNG APPARATUS Raymond L.Southern, New Kensington, and James K. Ely, Pittsburgh, Pa., assiguorsto Allegheny Ludlum Steel Corporation, Brackeuridge, Pa., a corporationof Pennsylvania Application November 22, 1954', Serial No.y 478,479

1 Claim. (Cl. 22-73) This invention relates to vacuum pouring apparatusand in particular to apparatus for vacuum Atreating molten metal as itis poured into a mold.

Recently the advantages of vacuum treating molten metal have beenrecognized and different complicated structures have been designed toeffect such vacuum treatment. The structures for vacuum treating moltenmetal which are known to the industry are massive in size and expensiveto produce and operate.

An object of this invention is to provide a relatively simple pouringapparatus for cooperating with a mold to permit evacuation of the moldand subject the molten metal to a vacuum treatment as the metal ispoured into the evacuated mold.

A more specific object of this invention is to provide a pouringapparatus disposed to be mounted -on a moldy to effect the evacuation ofthe mold and subject molten metal supplied thereto to a vacuum treatmentto degas the molten metal.

A further object of this invention is to provide, in a pouring apparatusdisposed to be mounted on a mold, a vacuum means for effecting theevacuation of the mold and the degassing of the molten metal suppliedthereto, and means for controlling the flow of the molten metal and formaintainingthe vacuum when the flow is interrupted.

Other objects of this invention will become apparent from the followingdescription when taken in conjunction -with the accompanying drawing,the'single figure of whichis a View iii-elevation and in section of 'avacuum pouring apparatus embodying the teachings of this invention.

Referring to the drawing, this invention is illustrated by reference toa vacuum pouring apparatus shown generally at for treating molten metal12 as it is poured from a ladle 14 into a mold 16. The pouring apparatusshown generally at 10 is formed of two component parts, namely a tundish18 and a vacuum chamber 20 assembled in sealed relation therewith, theunit being disposed to be seated on the upper rim of the mold 16.

ln general the tundish 18 is of usual construction, having metallicouter side walls 22 and a base 24 and being lined with a suitablerefractory material 26 and having a pouring nozzle 28 of refractorymaterial projecting downwardly through the base 24 of the tundish. Inthis embodiment, the tundish 18 is preferably provided with an inductioncoil 30 embedded in the refractory material 26 and disposed about thewell 32 for holding a supply of molten metal 12, and an induction coil34 also embedded in the refractory liner and disposed about the pouringnozzle 28. Each of the induction coils 30 and 34 is preferably of thehollow coil type disposed to have a cooling medium, such as water,circulated therethrough for the protection of the coils, and beingconnected to suitable induction heating generators (not shown) to beenergized thereby so as to prevent freezing of the molten metal 12 inthe tundish and nozzle thereof.

In order to control the flow of molten metal 12 through the orifice 36of the refractory nozzle 28-and to seal such orifice under predeterminedconditions, the tundish 18'v is y provided with a stopper rod 38 towhich is secured Aa rstopper V'40 of refractory material designed toseat in the nozzle 278 to prevent flow of the molten metal therethrough.The stopper rod 38 is protected from the molten metal 12 as by means ofa plurality of sleeves42 of refractory material assembled in end to endyrelation thereabout. Theupper end of the stopper rod 38 is secured to astopper carrier arm 44 as by means ofthe nuts 46, the stopper carrierarm 44 being secured to an end of a guide rod 48 which is disposed to beactuated by means of. an operating vlever 50 which is pivotly secured tothe other end of the guide rod as at 52. The guide rod 48 is carriedl ina guide 54 which is secured as by a link 56 'to a flange Y58 carried vbythe guide 54, whereby when pressure is applied to the end of theoperatingV lever 50 it will be pivoted to effect an actuation of theguide rod 48. l l y The vacuum chamber 20 is preferably formed as a sidewall member 60 disposed to extend downwardly from the base '24l of thetundish 18 about the nozzle 28, being secured to the base 24 to form aseal therewith as by means of a welded joint. Thevside wall member 60preferably terminates at its lower end in a rim member 62, having aconfiguration and size disposed to cooperate with the upper edge V64 ofa mold 16 for effecting a tight seal therewith. For this purposethelower edge of the rim 62 and the upper edge 64 of the mold 16 arepreferably formed of complementary configurations and are notched asat66 for receiving the gasket 68 of heat resisting material therebetweenwhereby a vacuum tight seal is formed between the rim member 62 `andtheupper edge 64 of. the-mold 16. Since the weight of the tundish 18 and ofthe molten metal 12 contained therein is-to be carried by the side Wallmember-60, suitable reinforcing ange members 78 areV disposed in spacedrelationto each other to extend between the base 24 and the innersurface of the side wall member 60 to provide adequate support therefor.The side wall member 60 is positioned to'extend downwardly from thetundish 18 about the pouring nozzle 28, whereby the pouringnozzle 28`and the orifice -36 thereof will be aligned with thev mold: 16 when thepouring apparatus 10- is seated `insealedfrelation on 'the mold 16 Inorder to evacuate the chamber 20 and the mold 16 prior to the pouring ofmolten metal therein, and to provide for continued evacuation of thechamber 20 during the pouring and after the mold 16 has been filled, thevacuum chamber 2() is provided with a conduit 71 having a ange coupling72 at its outer end disposed to be connected to a suitable vacuum pump(not shown). The vacuum pump should have sufficient capacity to providea vacuum of the order of 50 microns or less in the chamber 20 and mold16. A viewing port 74 is also provided for the vacuum chamber 20 wherebythe flow of molten metal into the mold 16 may be observed and the heightof the molten metal in the mold 16 can be determined so that theoperator of the apparatus can stop the iiow of molten metal to the mold16 when the metal reaches a predetermined height in the mold 16.

In operation the pouring apparatus 1G is seated on the upper edge 64 ofthe mold 16, and with the stopper 40 in a position to close the orifice36 for the pouring nozzle 28, the vacuum pump (not shown) is operated toevacuate the mold 16 and the chamber 20. In practice, if a Supply of themolten metal 12 is not contained in the tundish 18 when the apparatus 10is first positioned on the mold 16, a suitable wax or other sealingmedium (not shown) may be disposed about the stopper 40 for insuring aseal between the stopper 40 and the engaged surface of the pouringnozzle 28.

With the apparatus 10 positioned as described, and a hot top 76 ofsuitable refractory material disposed about the upper edge of the mold16 within the chamber 20, molten metal such as steel, ferrous andnon-ferrous base metals is poured from the ladle 14 into the tundish 18.With the vacuum in the chamber Z0 and the mold 16 at a predetermined lowlevel as determined by a gauge 78, the operating lever 50 is actuated toraise the guide rod 48 and lift the stopper 40 from its sealedengagement with the pouring nozzle 28. The molten metal 12 then flowsfreely through the nozzle 36 and the evacuated chamber 20 into the mold16. As the metal ows through the evacuated chamber 20 into the evacuatedmold 16 it is subjected to the vacuum treatment whereby gases such asoxygen, nitrogen and hydrogen and which are not in solution, are removedfrom the metal. As the mold is lled, gases are continuously removed fromthe metal flowing thereto and from the surface of the metal in the mold16, and after the mold 16 is filled and the stopper 40 is actuated to aclosed position to stop the tlow of molten metal to the mold 16, gasesevolving from the surface of the metal in the mold 16 are alsocontinuously removed. It is to be noted that the induction coils 30 and34, when energized, will prevent solidication of the molten metal 12 inthe tundish when the apparatus 10 remains on the mold 16 during thesolidication period of the metal in the mold 16. In practice, byWatching the rise of the level of the metal in the mold 16 by way of theviewing port 74, the llow of molten metal to the tundish 18 and fromthence to the mold 16 can be so controlled that as the mold is lled, theflow from the ladle 14 is stopped so that very little if any of themolten metal 12 remains in the tundish 18 when the mold 16 is lled. Thepresence of the hot top 76 on the mold within the vacu urn chamber 20controls the solidication of the metal 12 in the mold 16 so that theupper surface is the last portion to solidify and gases are removedcontinuously from such upper surface during the solidication period ofthe vacuum treated cast metal.

After the apparatus is disconnected from the vacuum pump, the apparatus10 can be readily removed from any given mold 16 and moved to anothermold as by means of lifting lugs (not shown), the only criterion beingthat the molds must have an upper edge for cooperating to receive therim 62 of the vacuum chamber 20 in a sealed relation therewith.

The apparatus is relatively simple in construction, but effective inoperation to degas molten metal as it is poured into a mold. A cleanerand more uniform cast ingot is obtained when the metal is vacuum treatedas described, as compared to the cast ingots obtanedby normal millpractice. Since the apparatus is relatively simple in construction, itwill be appreciated that it can be readily reproduced by anyone skilledin the art.

We claim:

In a vacuum pouring apparatus for degassing molten metal as it is pouredinto a mold, the combination comprising, a tundish for holding a supplyof the molten metal, a pouring nozzle for the tundish, a stopperdisposed for movement to open and close the nozzle, a wall memberforming a downwardly extending chamber secured at the upper end thereofto the tundish in a sealed relation therewith about the nozzle, the wallmember having a rim member at the lower end thereof having aconfiguration and size to seat on the mold to effect a tight jointtherewith, a plurality of spaced rib members connected between the wallmember and the tundish within the confines of the chamber to support thetundish and metal contained therein, communicating means connectedthrough the wall member of the chamber for evacuating the mold andchamber when the rim member is seated on the mold, means disposed to beoperated to move the stopper to an open position to permit the ow ofmolten metal through the evacuated chamber into the evacuated mold whilecontinuing the evacuation thereof to degas the molten metal, saidoperating means also being disposed to be operated to move the stopperto close the nozzle when the mold is lled to stop the flow of moltenmetal thereto while permitting continued evacuation of the chamber asthe metal solidities in the mold, and means disposed about the nozzleand tundish for maintaining the metal in the tundish in a moltencondition.

References Cited in the le of this patent UNITED STATES PATENTS 448,945Durfee et al. Mar. 24, 1891 2,123,659 Pike July l2, 1938 2,308,395Smithson et al Ian. 12, 1943 2,482,257 Frei Sept. 20, 1949 2,531,556Davis et al.` Nov. 28, 1950 FOREIGN PATENTS 2,831 Great Britain NOV` 14,1864 669,741 Germany Jan. 3, 1939

